Going against conventional wisdom, a new study suggests that multivitamins and some other supplements actually increase the odds of mortality.

This study and others like it show that there is little evidence to support the use of supplements to prevent chronic diseases, said lead author Jaakko Mursu, Ph.D., a nutritional epidemiologist at the University of Eastern Finland. His team collected data on almost 39,000 women with an average age of 62 over 19 years. They found that women who took multivitamins, vitamin B6, folic acid, magnesium, zinc, copper and especially iron died at higher rates during the course of the study than those who did not take supplements. Calcium was the only supplement shown to reduce the risk of death.

“We would advise people to reconsider whether they need to use supplements and put more emphasis on a healthy diet,” Mursu told Health Day News.

Duffy MacKay, vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, countered by telling Health Day News the “researchers started out with the intention of identifying harm. I caution against making overstated assumptions and conclusions from this data.”

The study was published in the Oct. 10 issue of the Archives of Internal Medicine.